The INUIT Research Unit (Ice Nuclei Research Unit)

The Research Unit “INUIT” (Ice Nuclei research UnIT) studies the heterogeneous ice formation in the atmosphere. The project is funded by the Deutsche Forschungsgesellschaft
(DFG). Phase 1 of the INUIT project lasted from January 2012 to December 2014 and Phase 2 runs from January 2015 – December 2017.

Ice crystals play an important role for the radiative properties of clouds as well as for the formation of precipitation. Mixed-phase clouds are clouds that consist of both, super-cooled liquid
droplets and ice particles. They account for a large fraction of the clouds in the atmosphere but our knowledge on the microphysical properties of these clouds is still limited. An important question
is how ice forms in these clouds. While it is well established that an ice nucleating particle is needed as a seed for the initial formation of an ice crystal in mixed-phase clouds many questions
remain on the concentration and variability of atmospheric ice nuclei and their physico-chemical properties.

Laboratory investigations are conducted on the nature of the nucleation process and on the chemical, microphysical, mineralogical and biological characterization of atmospherically relevant ice
nuclei as a function of temperature and water saturation. Intensive field experiments are conducted as well as monitoring surveys to study the number concentration, variability, size, chemical
composition, surface properties and sources of atmospheric ice nucleation particles. Modelling activities focus on the numerical assessment of heterogeneous ice nucleation and its importance for
cloud parameters. The results of the experimental investigations are assessed, state-of-the-art models are extended, and a closure study interlaces all three work packages.